Lord Darzi outlines the reasons why Londoners would benefit from a ban on smoking in parks

Smoking in London’s parks would become illegal under proposals submitted to the mayor, Boris Johnson, to make it one of the world’s healthiest cities.

Under the plans Johnson would use his powers to make bylaws banning smoking in Trafalgar Square and Parliament Square, and his influence over the Royal Parks – he appoints its board – to follow suit in its 10 green spaces, which include Hyde Park and Green Park.

The measures would create the first places in the UK where smoking outdoors is banned. In 2007 it became illegal to smoke in enclosed public spaces across the UK such as pubs, clubs and restaurants.

Johnson has been urged to take the bold step by experts belonging to the London Health Commission, an independent inquiry he set up in 2013 under the ex-Labour health minister and eminent surgeon Lord Darzi, to help persuade some of the city’s 1.2 million smokers to give up.

The advisers hope that London’s 32 local councils would follow the mayor’s lead and ban smoking in their parks and open spaces as well, which between them cover about 8,000ha (20,000 acres).

Professor Dame Sally Davies, the government’s chief medical officer for England, said it would help deter young people from smoking by reducing the likelihood of them seeing adults lighting up. “We all know smoking is bad for health,” said Davies, “so I welcome any measures to reduce both active smoking and its role-modelling in front of children.”

Michael Bloomberg, the former mayor of New York, said outlawing smoking in all of the city’s parks and on its beaches had helped increase life expectancy by three years during his 12 years in charge.

However Johnson – who aides say is “instinctively libertarian and not temporarily inclined to ban things” – hinted that he thought the plan was too interventionist. “One of the glories of London is that we are generally pretty laissez-faire about how people live their lives – provided they do not break the law and provided they do no harm to others,” he said.

He said he might act on the commission’s advice but only if he was convinced that doing so would save lives. “If we were to consider a ban on smoking in parks, we would need pretty clear evidence that this would have direct health benefits – in other words that it would actually save lives. It is time for London to have that debate.”

Sources at City Hall said London local authorities already had the power to ban smoking in their open spaces if they chose to and that Johnson was keen to see a pubic debate emerge about the commission’s suggestions. He will start a consultation with London Councils, which represents the 32 boroughs, on the issue.

Although smoking rates are falling, about 1.2m people in London still light up. Smoking-related diseases are estimated to cause 8,400 premature deaths and 51,000 hospital admissions a year in the capital.

Forest, the smokers’ rights group, said the ban would be “outrageous”. Simon Clark, director of Forest, said: “There’s no health risk to anyone other than the smoker. If you don’t like the smell, walk away.

“Tobacco is a legal product. If the chief medical officer doesn’t like people smoking in front of children she should lobby the government to introduce designated smoking rooms in pubs and clubs so adults can smoke inside in comfort.

“The next thing you know we’ll be banned from smoking in our own gardens in case a whiff of smoke travels over the fence.

“If Boris Johnson supports this move it will blow to smithereens his easy-going image. It will demonstrate he’s just like every other politician climbing the greasy pole, happy to micro-manage our lives and trample on ordinary people.”

Deborah Arnott, chief executive of Action on Smoking and Health (ASH), said: “We are delighted by the commission’s plan for smoking and tobacco control in London. We hope that the mayor of London will support it in full and announce that it will be a top priority.

“London needs to do more to tackle smoking which is the major cause of preventable premature death in the capital.”